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MEPS 291:307-312 (2005)
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Abstract
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First record of the at-sea swimming speed of a Pacific salmon during its oceanic migration
Hideji Tanaka1,2,7,*, Yasuhiko Naito1, Nancy D. Davis3, Shigehiko Urawa4, Hiroshi Ueda5, Masa-aki Fukuwaka6
1National Institute of Polar Research, 1-9-10 Kaga, Itabashi, Tokyo 173-8515, Japan 2Department of Social Informatics, Graduate School of Informatics, Kyoto University, Kyoto 606-8501, Japan 3School of Aquatic and
Fishery Sciences, University of Washington Seattle, Washington 98195-5020, USA 4National Salmon Resources Center, Fisheries Agency of Japan, 2-2 Nakanoshima, Toyohira-ku, Sapporo 062-0922, Japan 5Laboratory of Aquatic
Bioresouces and Ecosystem, Section of Ecosystem Conservation, Field Science Center for Northern Biosphere, Hokkaido University, Sapporo 060-0809, Japan 6Hokkaido National Fisheries Research Institute, Fisheries Research Agency 116
Katsurakoi, Kushiro 085-0802, Japan 7Present address: COE for Neo-Science and Natural History, Graduate School of Fisheries Sciences, Hokkaido University, 041-8611 Hakodate, Japan
*Email: htanaka@nature.sci.hokudai.ac.jp

ABSTRACT: The swimming behavior of the chum salmon Oncorhynchus keta was studied for 53 d of its 67 d oceanic migration from the central Bering Sea to the Japanese coast. We provide the first data on swimming speeds by a homing salmon, recorded at
5 s intervals by a fish-borne time-speed, depth, and temperature logger. Swimming speed rarely exceeded 1.0 m s1, and horizontal swimming speed was 36.4 ± 15.2 km d1. Cumulative horizontal swimming distance was
approximately 2500 km, equivalent to 90% of the minimum distance between the release and recovery sites (2760 km). Swimming depth and speed peaked around dawn and dusk, and there was a smaller peak around midnight. The fish showed sequential up-and-down
movement near the thermocline during daytime. Diurnal patterns of movement suggest that homing chum salmon spend a considerable time foraging, and the strategy is different between daytime and nighttime. Our findings indicate that over large distances of
ocean, a homing salmon maintains a strong homeward orientation, but that passive transport by favorable water currents may help the migration.
KEY WORDS: Chum salmon · Oceanic migration · Swimming speed · Orientation · Time allocation · Foraging behavior
Full text in pdf format

Published in MEPS Vol.
291
(2005) on April 28
Print ISSN: 0171-8630; Online ISSN: 1616-1599.
Copyright © Inter-Research, Oldendorf/Luhe, 2005
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